Lecture "Plankton photosymbiosis in the oceans"
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Photosymbiosis is a symbiotic relationship between two or more organisms, one of which is capable of photosynthesis. As in marine benthic environments (e.g. coral reef ecosystems), photosymbiotic associations are frequently encountered among plankton in marine pelagic environments and can involve various combinations of microalgae with bacteria, protists, or metazoans. After a brief overview of current knowledge on the diversity of the organisms involved in mutualistic pelagic photosymbioses, I will focus on Radiolaria (Rhizaria) a poorly studied yet significant plankton group in oceanic ecosystems.
Evolutionary relationships based on single cell morpho- molecular approaches for main radiolarian groups and their microalgal symbionts emphasize the necessity to re-evaluate traditional classification structures. Those molecular phylogenies using universal taxonomic marker genes (e.g. 18S rDNA) also provide references sequences that are critically required to appropriately annotate environmental meta-barcoding datasets and explore specific ecological patterns in relation to contextual parameters. In order to investigate further the functioning of photosymbiotic relationships between protists, I'll present preliminary results based on comparative genomic and single cell stable isotopes approaches.